Asustek's Padfone X Mini, which can be used either as a smartphone or a tablet, will be available in the U.S. starting next week.

At the heart of the Padfone X Mini is a 4.5-inch LTE smartphone, which can be slid into a companion dock to be used as a tablet. The dock has a 7-inch screen.

The dual-function gadget, which runs on Google's Android 4.4, will be available Oct. 23 from AT&T for $199 with a two-year mobile contract. Other retailers will start selling the device in November. Asus has not shared information about worldwide availability.

The Padfone X Mini is a smaller version of the Padfone X, which is a 5-inch smartphone that can be used as a 9-inch tablet when docked. But the larger Padfone X has a Qualcomm processor, while the Mini variant has an Intel Clover Trail+ chip, which is close to two years old.

The Padfone X Mini has a 5-megapixel camera. The dock has a second SIM card slot and a battery that can charge the smartphone.

A lot of companies have tried to unite laptops and tablets, but Asus is one of the few to fuse a smartphone and tablet. Motorola in 2011 sold an Atrix 4G smartphone that could dock into a laptop, but the device wasn't widely adopted.

Intel and Asus earlier this year signed an agreement to jointly develop mobile products.